Starting switch



Aug. 9, 1949. F. w. MURPHY 2,478,305

STARTING SWITCH Filed June 24, 1946 IN VEN TOR.

[gar 0g Patented Aug. 9, 1949 UNITED STATES PATENT OFFICE STARTING SWITCH Frank W. Murphy, Tulsa, Okla.

Application June 24, 1946, Serial No. 678,716

2 Claims. 1

This invention relates to safety switches of the type used on stationary engines and is an improvement over my prior patent, Number 2,358,- 729, dated September 2944..

It is customary in the use of large stationary engines to permit the engines to run unattended for long periods of time and safety switches of this type may be used to stop the engine upon loss of oil pressure by grounding out the magneto of the engine. Heretofore in the use of such switches it has been necessary to provide a starting switch for breaking the safety switch circuit when starting the engine and then to close the starting switch when the engine is started. There is always the possibility that the operator will fail to close the starting switch after the engine starts, thus leaving the safety switch out of 033- eration.

It is an object of this invention to provide a safety switch of this type in which means are provided for opening the switch circuit for starting and when a predetermined pressure is reached the switch will automatically be in condition for use without the necessity of the operator closing a switch.

Another object of this invention is to provide a safety switch of the kind described, wherein contact is made by the pointer and a fixed contact for grounding a magneto to stop the engine and means for holding the pointer out of contact with the fixed contact while the engine is being started which means are reieased when a determined pressure is reached.

With the above and other objects in view, my invention consists in the arrangement, combination and details of construction disclosed in the drawings and specifications, and then more particularly pointed out in the appended claims.

In the drawings, wherein similar reference characters designate similar parts throughout the respective views,

Figure 1 is a front elevation of an electric safety switch constructed according to an embodiment of my invention and showing diagrammatically the electric circuit associated therewith,

Figure 2 is a rear elevation of the switch, and

Figure 3 is a detail front elevation, partly broken away.

Referring to the drawings, the numeral l0 designates generally a standard or conventional type Bourdon gauge, used for indicating pressure, and is equipped with electrical contacts and an indicator moving or contact breaking device of my invention.

The gauge I0 is formed with a Bourdon spring tube ll within the casing [2 having a link [4 connecting the free end of tube ii to the lever !5 which actuates the metal indicator needle IS. The lever i5 is formed with a substantially U- shaped lever arm H on one side of the pivot l8 and the link it attaches to the end of one arm of the U-shapc lever arm i'i whereby expansion and movement of the tube i I will rock lever arm 55 engaging the indicator needle 16 causing needle E5 to be moved about its pivot point 19.

On the face of the dial 2!} a fixed contact 2| is secured. The contact 2| extends through the casing l2 and is insulated therefrom. The contact 25 is adapted to be engaged by the needle it when the needle reaches a certain predetermined point, in this case with use on an oil gauge the zero indication. The needle l6 and contact 2| are connected in the wiring circuit of the ignition system using a magneto 22 whereby the magneto 22 is grounded when the needle i6 engages the contact 2 i.

In the wiring circuit of the ignition system a wire 24 connects the magneto E2 to ground and a wire 25 connects the magneto 22 to the ignition system. A wire 26 is connected between wire 25 of the circuit to the fixed contact 2! and a wire 27 connects the needle is and case l2 to ground. In this arrangement, when the needle to is not engaging the contact 2! and the engine is running, the magneto 2! will be connected into the ignition circuit, and when, for any reason, the oil pressure should drop to zero, the magnet 22 would be grounded through contact 21 and needle Iii thereby stopping the engine to prevent damage thereto.

The engine cannot again be started unless the grounding circuit through the gauge I0 is broken. Heretofore, it has been necessary to use a switch in this gauge circuit to be manually operated and an operator would open this manual switch until the engine was started and sufficient oil pressure built up to move the pointer it away from contact 2! at which time it was necessary for the operator to close this manual switch so the safety gauge would again be in position to stop the engine in case of further failure. Frequently, when the engine is re-started, the operator would forget to close the manual switch and if the oil failure should again occur, the safety switch would not stop the engine. It would be desirable to provide means for breaking the switch circuit manually to start the engine and automatic means for returning the circuit to operable condition without the necessity of an operator closing the manual switch. I have provided means for attain- 3 ing this automatic condition, by the use of a cam device engageable with the pointer linkage.

This device consists of a pin 28 rotatably carried by the rear wall of the housing [2. The pin 28 extends outwardly from the housing I2 a short distance so that a button 29 may be fastened thereto, and extends inwardly of the housing l2 a distance sufiicient to engage the U- shaped lever arm ll of the indicator actuating arm IS. The pin 28 is partially cut away at its inner end to form a cam 30. The cam 30 has an annular surface of the same diameter as the pin 28 and a flat surface which is substantially a chord of the pin 28, so that in the normal operating position the flat surface is adjacent the U-shaped arm of lever l and is spaced slightly therefrom, whereas in reset position the annular face of cam 36 engages the lever arm I! and moves it about its pivot 18 thereby moving the indicator needle 16 a predetermined distance about the scale on the face of the gauge ID.

A light coil spring 31 is coiled about the pin 28 within the casing i2 one end of which is fixed to the pin 28 and the other end engageable with or fixed to the casing A2, in such a manner that the spring 3| constantly urges the pin 28 to the normal position wherein the pin 28 is out of engagement with the lever arm ll.

A stop pin 32 is fixed to and extends from the pin 28 and is engageable in the reset position with a stop 34 fixed to the rear wall of the casing l2.

In the use and operation of this improved safety switch, for starting an engine where it is necessary to open the circuit through the switch and gauge ii), the operator merely turns the button 29 to its extreme position when the stops 32 and 34 are in engagement and the round surface of cam 30 presses the lever arm H upwardly and the lever i5 moves the pointer IE to a predetermined position out of engagement With contact 2i, yet Well below the normal operating pressure indication. The engine may now be started and as the oil pressure builds up in the system and becomes greater than the setting of the indicator needle 16, the oil pressure tube I i will move the lever arm H out of engagement with the cam 30 and the spring 3i will return the cam 30 to the original position with the fiat surface facing the lever arm l'l, so that upon loss of oil pressure as the indicator 16 reaches the Zero or other predetermined position, it will engage the contact 2! to ground out the magneto and thereby stop the engine.

I do not mean to confine myself to the exact details of construction herein disclosed, but claim 4 all variations falling within the purview of the appended claims.

Having thus described my invention, what I claim is:

1. In a combined gauge and switch having an expansible gauge actuating tube, a pointer on said gauge and a contact member engageable with said pointer, a rockable lever pivotally mounted in said gauge for actuating said pointer, a U-shaped arm on said lever, a link connected between said tube and said lever arm, a cylindrical reset pin rotatably mounted in said gauge, said pin formed with a peripheral recess on one side thereof within which said lever arm is adapted to be disposed when the pointer is in engagement with said contact member, the remaining surface of said pin constituting a cam engageable with said lever arm for holding the pointer out of engagement with said contact member prior to operation of said pointer by said tube, and spring means for rotating said reset pin to said first mentioned position, whereby said pointer may again contact said contact member upon failure of operation thereof by said tube.

2. In a combined gauge and switch having an expansible gauge actuating member, a rotatable pointer and contact member on said gauge, a fixed contact member engageable with said pointer, a pointer actuating lever pivotally mounted between said actuating member and said pointer, a rotatable reset pin engageable with said lever for holding said pointer out of engagement with said fixed contact prior to actuation of said pointer by said actuating member, said pin disposed in the normal position thereof out of contact with said lever, a cam on said pin engageable with said lever upon rotation to a second position for holding the pointer out of engagement with said fixed contact, and a spring operatively connected with said pin for returning the pin to the normal position upon movement in one direction of said pointer away from said cam by said expansible member.

FRANK W. MURPHY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,374,635 Cleveland Apr. 12, 1921 1,589,545 Newkirk June 22, 1926 1,833,996 Johnstone et a1. Dec. 1, 1931 2,384,562 Murphy Sept. 11, 1945 

